World War 2 was fought on the Mediterranean, the Pacific and the Atlantic, and in four major land campaigns; in the Soviet Union, North Africa and the Mediterranean, Western Europe and the Far East. No less than 56 companies were involved.

The Second Battle
of the Atlantic was the longest continuous military campaign
of World War II, running from 1939 right through to the defeat of Nazi Germany

in 1945, and was at its height from mid-1940 through
to about the end of 1943. The naval battle pitted Nazi
Germany's U-boats against convoys from North America
to the United Kingdom, protected mainly by the British
and Canadian navies and air forces, which were later
aided by United States forces.